Field
The disclosed concept pertains generally to electrical switching apparatus, such as, for example, circuit breakers. The disclosed concept also pertains to stored energy assemblies for circuit breakers.
Background Information
Electrical switching apparatus, such as circuit breakers, provide protection for electrical systems from electrical fault conditions such as, for example, current overloads, short circuits, abnormal voltage and other fault conditions. Typically, circuit breakers include an operating mechanism which opens electrical contact assemblies to interrupt the flow of current through the conductors of an electrical system in response to such fault conditions as detected, for example, by a trip unit.
Some medium voltage circuit breakers, for example, employ a spring-operated stored energy assembly. Specifically, the operating mechanism of such circuit breakers typically includes an opening assembly having at least one spring which facilitates the opening (e.g., separation) of the electrical contact assemblies, a closing assembly including a number of springs that close the electrical contact assemblies, and a charging mechanism for charging the spring(s). The contact assemblies are closed by releasing the stored energy of the closing assembly spring(s). The closing assembly spring(s) is/are charged either manually, using a manual charging mechanism such as, for example, a charging handle, or automatically using, for example, a motor-driven charging mechanism or other suitable electromechanical charging mechanism. Each of the manual and automatic charging mechanisms of known stored energy assemblies requires its own individual “chain” or assembly of components, in order to link the corresponding power source (e.g., human power; motor power) to the spring(s) that must be charged.
Typically, there are clutch units between the charging mechanisms and the spring(s) that regulate the power being transmitted to the springs. It is known to employ compression springs as the springs that regulate the power to be transmitted. However, employing compression springs often results in an unbalanced force on the transmission shaft, and a significantly increased volume of space being taken up. It is also known to employ clock springs as the springs that regulate power. However, known clutch units for stored energy assemblies employing clock springs often have a significant number of parts and as a result, are relatively difficult to assemble/manufacture. Furthermore, such clutch units are also not compact.
There is thus room for improvement in electrical switching apparatus and in stored energy assemblies therefor.